Method for on-line estimation of internal resistance of power lithium battery

Abstract

The invention relates to a method for on-line estimation of internal resistance of a power lithium battery. The method for on-line estimation of the internal resistance of the power lithium battery comprises the steps that an automobile is energized to travel, and a battery management system obtains the working condition of the automobile in real time; a current changing curve graph with the working condition same as or close to the real-time traveling working condition of the automobile is selected according to the real-time traveling working condition of the automobile; the maximum current value I1 and the minimum current value I2 in the current changing curve graph are selected; in the process of traveling discharging process of the automobile, when the current value at present is equal to the maximum current value I1, the battery voltage value at the moment is recorded as the minimum voltage value U2; when the current value at present is equal to the minimum current value I2, the battery voltage value at the moment is recorded as the maximum voltage value U1; the formula R=(U1-U2) / (I1-I2) is used for calculating the battery direct-current resistance R. Compared with the prior art, an auxiliary device or other externally-connected measuring devices are not needed, internal resistance value of the power battery can be estimated in an on-line mode in the traveling process of the automobile, the method is used only according to real-time battery voltage data and real-time battery current data in the traveling process of the automobile, and the method is simple, easy to implement, practical, and easy to popularize and use.

Description

technical field [0001] The invention relates to the technical field of automotive power lithium batteries, in particular to a method for estimating the internal resistance of power lithium batteries online. Background technique [0002] Battery internal resistance is one of the most important characteristic parameters of a battery, and it is also one of the important indicators for evaluating battery performance. It can evaluate battery health, battery life estimation, system SOC estimation, power output / input capacity, and other battery operating conditions. Important parameters can also be used as the basis for evaluating whether the battery is damaged or faulty, or whether there is a problem with the connection of the battery. In the actual application of the battery management system, it is very necessary to estimate the real-time value of the internal resistance of the battery online. [0003] The internal resistance test includes AC internal resistance and DC internal...

AI Technical Summary

Problems solved by technology

[0004] At present, most of the estimation of internal resistance is carried out in the theoretical stage, laboratory modeling test or vehicle external auxiliary equipment for internal resistance estimation, but during the driving process of electric vehicles, due to the limitations of test equipment and hardware platforms, external assistance cannot be added Equipment or other test equipment for measurement, and the change of current can only be determined by the actual driving conditions of the electric vehicle, it is impossible to use the laboratory measurement method to estimate the DC internal resistance online in real time, and the vehicle cannot be measured by external measuring equipment while driving , so it is impossible to estimate the internal resistance of the battery in real time online

Images